Typically, in a fixing device, a heat source is mounted on an image forming apparatus and a lamp emits infrared rays to transpose type onto a medium. In some embodiments, a halogen lamp may be utilized to perform the transposition via electromagnetic induction.
In general, fixing devices include a heating roller (or a fixing belt with a plurality of rollers disposed thereon) and a press roller. However, it is necessary to reduce the heat capacity of each component as much as possible and to further concentrate heating areas of the fixing device in order to maximize overall thermal efficiency. Furthermore, typical heating widths are wide, thus making it difficult to intensively provide widely distributed thermal energy to a nip portion as a way to optimize thermal efficiency.
Furthermore, fixing quality within the fixing device for an electronic photograph is affected if heat generated unevenness is present in a paper transport direction (a first direction) and in a perpendicular direction. Particularly, with respect to color printing, heat generated unevenness produces differences in color developing and/or generates a gloss-like appearance.
Additionally, in a fixing device in which heat capacity has been significantly reduced, additional problems with respect to speed irregularity, warp or deterioration of the belt, and/or expansion of the transport roller exist in that the temperature section of the fixing device through which paper does not pass (non-paper passing area) is increased dramatically. Due to energy conservation concerns, heating of the section of the non-paper passing area is not preferable. As such, due to environmental concerns, an apparatus or method that provides energy to the nip portion which heats only the passing area of the paper or the image forming area in the paper has become an area of focus in the field.
In some cases, a silicone rubber layer is provided to the belt of the fixing device. A difference in temperature between the heater and the belt is generated via thermal insulation with the silicone rubber layer, and therefore temperature control helps to maintain the nip area at a predetermined fixing process temperature. However, it is difficult to control the non-paper passing area as the temperature therein rapidly changes. Furthermore, high image quality is maintained via precise temperature control when heat generation is performed by dividing a resistance heating body. As such, it is often useful to control the temperature separately in each division unit; however, overall device size may be increased due to the measurement and control devices.